180 



SOIL PHYSICS AND MANAGEMENT 



while the oblique form would give 25.95 per cent. The air space 

 with columnar arrangement may be calculated very easily by taking 

 a one-inch cubical box and filling it with marbles of different sizes, 

 varying from one inch to one-sixteenth inch in diameter, and coni- 



c 



FIQ. 87. 



puting the per cent of air space left in the box. The same calcula- 

 tion may be made for the oblique arrangement, although it is much 

 more difficult because of the mathematics involved. 



If instead of having solid particles, as in figures 88A and B, 

 A B c 



Fn. 88. Diagram showing the arrangement of soil particles. A, columnar or vertical; 

 B, oblique; C, compound granules. 



each of these should be a compound granule (Fig. 880) made up 

 of many spherical particles with the same arrangement as the larger 

 particles, the air space or porosity would be. for columnar arrange- 

 ment, (47.64 per cent + 47.64 per cent of 52.36 per cent)= 72.5ft 

 per cent, or, for oblique arrangement (25.95 per cent + 25.95 per 



